Table variables store a set of records, so naturally the declaration syntax looks very similar to a CREATE TABLE statement, as you can see in the following example: You might think table variables work just like temporary tables (CREATE TABLE #Product Totals), but there are some differences.1) Add, drop, modify table columns 2) Add and drop constraints 3) Enable and Disable constraints The SQL RENAME command is used to change the name of the table or a database object.If you change the object's name any reference to the old name will be affected. An updatable view is one which allows performing a UPDATE command on itself without affecting any other table. The view is defined based on one and only one table. The view must include the PRIMARY KEY of the table based upon which the view has been created. The view should not have any field made out of aggregate functions. The view must not have any DISTINCT clause in its definition. The view must not have any GROUP BY or HAVING clause in its definition. The view must not have any SUBQUERIES in its definitions. If the view you want to update is based upon another view, the later should be updatable. Any of the selected output fields (of the view) must not use constants, strings or value expressions.SELECT * FROM example_timestamp; ---- -------------------------- --------------------- | id | data | cur_timestamp | ---- -------------------------- --------------------- | 1 | The time of creation is: | 2004-12-01 | ---- -------------------------- --------------------- 1 row in set (0.00 sec)mysql SELECT * FROM example_timestamp; ---- --------------------------- --------------------- | id | data | cur_timestamp | ---- --------------------------- --------------------- | 1 | The current timestamp is: | 2004-12-01 | ---- --------------------------- --------------------- 1 row in set (0.01 sec) retains its initial value and is not changed during subsequent updates.